This invention relates to an apparatus for continuous electroforming/electrodeposition, and a process for using the same. More particularly, this invention relates to a semi-step carousel electroforming/electrodeposition apparatus that permits rapid, continuous and automated processes for electroforming or electrodepositing metal or metal alloys on mandrel surfaces. The products produced by the apparatus and process of the present invention may be utilized in a broad range of finished articles. For example, the products produced by the present invention may be used for electrostatic imaging members, endless and seamless electrostatographic belts, tensile segments for continuously variable transmission belts, reinforcement members for conventional "V" belts, timing belts and flat belts, donor rolls, fuser rolls, etc.
Electroforming, electrodeposition and electroplating methods and apparatus are well known in the art. For example, U.S. Pat. No. 4,067,782 discloses a process for nickel plating a cylindrically shaped hollow core mandrel. The mandrel is suitable for chromium plating and for use in an electroforming process for the production of endless, seamless belts for electrostatographic applications. The process comprises anodizing a hollow aluminum core, nickel plating the anodized core, optionally subjecting the plated core to an acid dip bath and thereafter plating the core with chromium.
U.S. Pat. No. 4,501,646 discloses an electroforming process comprising providing a mandrel having certain coefficient of expansion characteristics and length to segmental cross-sectional area ratios in an electroforming bath to electroform a coating of a metal on the core mandrel and thereafter removing the coating under certain cooling conditions.
U.S. Pat. No. 3,844,906 discloses a process for forming seamless nickel belts on a mandrel and removing the nickel belt from the mandrel under certain cooling conditions.
U.S. Pat. No. 4,024,045 describes a master pattern cylinder comprising a roller body and a sleeve surrounding the roller body. In one embodiment, a thin-walled sleeve is described having an outer surface which is cylindrical and an inner surface which is frustum-shaped. In another embodiment, a roller body is fitted with a thin-walled sleeve having cylindrical inner and outer surfaces. The mandrel may be employed for producing perforated nickel sleeves by electrolytic deposition.
U.S. Pat. No. 4,530,739 describes a method of fabricating an electroplated substrate. The substrate is prepared in an electroforming process by electroplating onto and removing a metallic layer from the surface of a specially prepared mandrel. The surface of the cylindrical mandrel is substantially defect-free and may either be textured or smooth prior to electroplating a metallic layer thereon.
U.S. Pat. No. 3,669,849 discloses an electrodeposition process using a mandrel having a surface with recessed areas, and a means for facilitating electrodeposition in the recessed areas.
Use of a carousel apparatus for electroplating articles is also known in the art. For example, U.S. Pat. No. 4,734,179 discloses a carousel electroplating apparatus used to plate copper onto cast or swaged lead alloy bullet cores. The carousel apparatus contains positions for placing each of multiple bullet cores between two respective unshielded anodes, and the entire carousel apparatus is suspended in an electrolytic bath to complete the electrodeposition process. After the electrodeposition is completed, the carousel apparatus is removed from the electrolytic solution, and the plated bullet cores are removed.
Use of shielding around electrodes in an electroforming process is also generally known in the art. For example, U.S. Pat. No. 4,902,386 discloses the use of shades and/or varying porosity screens that can be positioned within the electroplating bath to control the plated coating thickness on the mandrel. Similarly, use of shields in an electrodeposition tank is disclosed in U.S. Pat. Nos. 4,478,769 and 5,156,863. These patents disclose that a shield of non-conductive material may be placed between the electrode and the mandrel to control the deposition of metal ions on the mandrel surface.
The conventional electrodeposition processes, however, possess several problems and disadvantages. For example, conventional processes using a carousel apparatus do not allow for the independent control of thicknesses on each individual mandrel so as to allow the production of different products in the same carousel. Furthermore, conventional carousels often are very large and are therefore not conducive to large scale industrial application. Conventional electrodeposition methods also exhibit problems in creating products which have a uniform thickness.
A further problem with conventional electrodeposition methods is that such methods using nonrotating mandrels have only limited applications. Processes using nonrotating mandrels may be preferred, for instance, so as to eliminate the need for additional moving parts in the apparatus and the associated maintenance of those parts and to ease the fabrication of product materials. Additionally, use of rotating mandrels requires that electricity be transmitted through the rotating member, which can cause arcing and sparking, which can accelerate wear and the need for maintenance of the apparatus. However, conventional processes using nonrotating mandrels are severely limited. For example, such processes are limited to electroforming or electroplating mandrels having a diameter less than about one inch. If larger diameter mandrels are to be used, the apparatus becomes exceptionally large, requiring an anode-to-mandrel distance of up to four feet or more.